Most likely muslin for the caps, a heavy broadcloth or homespun type material for the aprons. The aprons had to be able to stand up to a LOT of wear and washing. Most people only had 3 or 4 changes of clothes (and this number included their nightclothes), and women had many many different aprons that they would wear to protect their dresses. When something was spilled, you just washed your apron instead of having to wash your dress. That way your clothes lasted a lot longer. Washboards are brutal!